This application claims benefit of Japanese Patent Application No. 2003-387654 filed on Nov. 18, 2003, the contents of which are incorporated by the reference.
The present invention relates to liquid crystal display apparatus and, more particularly, to a rubbing roll apparatus for executing an orientation process on a glass substrate surface of the apparatus and a method for manufacturing a liquid crystal display apparatus using the same.
Liquid crystal display apparatus (or liquid crystal display panel) is relatively thin and consumes low power, and is thus broadly spread as display units of personal computers and those of car navigation apparatuses.
A liquid crystal display is usually formed by disposing face-to-face and at a very small distance two thin glass panels having electrodes of TFTs (Thin Film Transistors) formed thereon and filling liquid crystal in the space between these glass panels. These glass panels have respective orientation films formed on their inner surfaces, and these orientation films are subjected to a predetermined orientation process, thereby obtaining orientation of the sealed liquid crystal. The orientation process is usually carried out by using an orientation processing apparatus, i.e., a rubbing roll or rubbing apparatus.
Heretofore, various types of orientation processing apparatus have been proposed. As a typical prior art orientation processing apparatus, a rubbing apparatus has been disclosed, which is formed by applying a rubbing cloth with a double-side bond tape or the like to the surface of a cylindrical rotational roller (see Literature 1: Japanese Patent Laid-open No. 2000-171803, for example).
FIGS. 3(A) and 3(B) show an example of such a prior art orientation processing apparatus. FIG. 3(A) is a perspective view, and FIG. 3(B) is a developed view of a rubbing cloth. As shown in FIG. 3(A), this prior art orientation processing apparatus 30 comprises a cylindrical rotational roller 31 and a plurality of rubbing cloth pieces 32 provided on the outer periphery (i.e., peripheral surface) of the rotational roller 31 and extending substantially parallel to the axis of the rotational roller 31. These rubbing cloth pieces 32 are applied by using a double-side bond tape or the like such that their adjacent edges abut, i.e., form contact seams 34. This orientation film processing apparatus 30 is used for the orientation process such that it is rotated on and rubs an orientation film, which is printedly formed on, for instance, a glass panel of a liquid crystal display apparatus. In this case, as shown in the developed view in FIG. 3(B), a circumferential pattern of a plurality of seams 34 is formed
FIGS. 4(A) and 4(B) show a different orientation processing apparatus disclosed in the Literature 1. FIG. 4(A) is a perspective view, and FIG. 4(B) is a developed view. This orientation film processing apparatus 40 comprises a cylindrical rotational roller 41 and a relatively thin rubbing cloth piece 42 helically wound on the outer periphery of the rotational roller 41 such that the edges of adjacent turns are in contact with each other. Also this rubbing cloth 42 is applied to the outer periphery of the rotational roller 41 at an acute angle to the direction perpendicular to the axis of rotation by using a double-side bond tape or the like. Thus, as shown in the developed view 43 of FIG. 4(B), a pattern of a plurality of inclined seams 44 is formed.
Display panels such as liquid crystal display apparatuses are increasing in size more and more, and their price competition becomes harder and harder due to mass production. In such large-size liquid crystal display apparatuses, the panel size is naturally increasing in size. However, the use of the above orientation processing apparatus or rotational roller necessitates a wide cloth piece, which is applied as rubbing cloth substantially parallel to or at an edge to the axial direction. The manufacture of wide cloth has a problem that it is difficult to obtain uniform stretch by applying a predetermined stretching force in the axial direction, thus leading to lack of pile length uniformity and increase of possibility of occurrence of abnormal orientation. In the case of helically winding a narrow rubbing cloth piece on the outer periphery of the rotational roller, the direction of pile for raising is determined by the rubbing cloth application angle, thus forming a seam at a predetermined angle from the circumferential direction. This causes the portion which has not been uniformly rubbing-processed.